Toshiba CTX28 Connecting RBSU/RBSS Station Devices NT-Mode, Rbsu to NT1 Point-to-point Connection

ISDN Interfaces

RBSU/RBSS Interface Units

Most NT1 devices have TR option switches; if the NT1 does not have TRs, two 100-ohm TRs must be wired into the NT1 modular jack - one 100-ohm resistor across each pair (Tx and Rx). Refer to the NT1 manufacturers documentation for the maximum loop length between the NT1 and the network jack. The maximum loop length between the NT1 and the RBSU circuit is 1650 feet.

RBSU

TE-Circuit

Switch in

100-ohm TR using RBSU option switch.

	RJ45 Pinout			RJ45 Pinout
(RBSU - BRI jack)			(NT1 - S/T jack)
			BRI
		(four-wire)
3				3
		TX	RX
6		TX	RX	6
4		RX	TX	4
5		RX	TX	5

BRI

(two-wire)

4 RX/TX

NT-1

Switch

in 100-ohm 5 RX/TX

TR.

Network

BRI-line

RJ11 Jack

5433

T

Note: T and U are ISDN standard reference points.

Local AC Power

U

Demarcation Point

Figure 7-17 RBSU to NT1 Point-to-point Connection

Connecting RBSU/RBSS Station Devices (NT-Mode)

S-type TAs and TE-1s can be connected to the station side of TBSU, RBSU, and RBSS circuits. TA and TE devices must be powered by local AC power using AC adapter supplied with the TA or TE device. The RBSU/RBSS circuits must be configured in the NT mode when connected to TA and TE devices (refer to option switches in Table 7-8 on page 7-17and Table 7-11 on page 7-22).

The TA enables you to connect non-ISDN voice and data devices to ISDN BRI circuits. The TA matches the protocol of existing interfaces (R-reference point) to the ISDN S/T protocol (see Figure 7-1 on page 7-2). TA devices include asynchronous circuit-switched adapters that convert RS-232 sync data (like data from a PC COM port) to B-channel 64 kbps sync.

TAs also enable you to connect standard telephones and non-ISDN fax machines to receive and make calls over ISDN circuits. TEs include any user device (telephone, fax, PC video conference board) that is designed to plug directly into the ISDN (S/T) interface without the use of a TA.

There are two types of ISDN TA and TE-1 devices: the U-type and the S/T type. Most manufacturers of ISDN station devices make both types. On the RBSU/RBSS station side, BRI-NT circuits only function with S/T type TA and TE-1 devices. You cannot connect U-type TE-1 or TA devices to the RBSU/RBSS BRI-NT circuits.

Also, connecting an NT1 to the RBSU/RBSS BRI-NT circuit to convert from S/T to U interface is not supported to enable the use of U-type TE-1 or TA device on the station side of the RBSU/ RBSS. U-type TE-1 and TA device interface is provided in the Strata CTX by the RBUU/RBUS BRI circuit only.

The RBSU/RBSS BRI-NT circuit supports the National ISDN 2 (NI2) S-Interface “passive bus.” It is called a passive bus, because it contains no logical functions. The RBSU/RBSS BRI-NT interface supports a point-to-multipoint connection on two twisted pairs. Up to two TE-1 and/or TA devices can be connected to one RBSU/RBSS, BRI-NT circuit. Using standardized wiring and

7-24 Strata CTX I&M 06/04